SQL and IIS error when publish an ASP .NET application to IIS

I have added a database to my application and then published it in IIS. I am getting an SQL error and IIS error when trying to browse to the site and have been trying to figure it out all day. I hope you can look and see if you can come up with something. The IIS error is: "Cannot open database "KML" requested by the login. The login failed. Login failed for user 'NT AUTHORITY\SYSTEM'". The SQL error is: "[SqlException (0x80131904): Cannot open database 'KML' requested by the login. The login failed. Login failed for user 'NT_AUTHORITY\SYSTEM'. ] . I hope someone can figure out what the problem is. Thanks.

When you publish a website to iis it typically runs under the identity of the application pool and for new sites a new pool is created, named after the site and having a windows user of IIS AppPool\site-name-here. To have a connection to the db work out with Windows mode authentication you need to make a user/login in the database with a name that matches the application pool

In your case you're running your site on an app pool that seems to use ntauthority\system (local system) as it's identity. This is a monumentally bad idea; anyone who finds a way to exploit it will gain admin privileges to the entire machine. Notwithstanding throw, you'll still need to make a login and map the user to it for the KML database in order for that user to be able to log into the db using Windows auth